Pump housing



22 1950.4 1 vR. PQMccuLLoc-l 519,588 Pun? HOUSING mea nec. 24. 194s.

- speed, such as required when UNITED ,PATENToFI-lcf v PUMP noUsmG Robert P. I Vfciiullmzln,"Fox Point, Wis., assignor, by a mesne assignments, to Borg-Warner Corporation, l(Jh'icago, Ill.; a corporation of Illinois Application December' a4, 194s, serial No. 515,574

The present invention relates to fluid displacey ment apparatus, and it has particular reference to structures of this character that are emp1oyedfor supercharging aircraft engines. The subject mattei'V of this invention is a continuation in partof theapplication of Robert P. McCulloch Serial No. 504,920 filed September 2'Z, y1943 issued as Patent No'. 2,491,677 dated December 20, 1949.

One of the principal objects of the present inventionsis to simplifythe construction of uid displacement apparatus /such as superchargers,

and to improve the eiliciency, operation and de'- V pendability of such apparatus.y

4An object of the improvements is tomaterially.

reduce the weight of the apparatuswithout affecting the strength of the structural parts or decreasing the eiliciency of its operation; a

Another object resides in providing a fluid displacement apparatus wherein the housing walls l are made ofa light-weight metal such as an aluminum alloy, and the work-faces of said walls, -that are proximate to the rotors, are provided with a liner that is preferably asteel sheet that is a harder material than the aluminum alloy arid 'eects a snug flt with respect to the rotor with'which the lineris engaged.- The liner may be'securedin any suitable manner to the work faces of the` housing, andthe portions ofthe rotors thatcoact therewith are provided with ridges or lands. After assembly of the pump, the rotors are operated at`a desirable speed to`cut or wear away the contacted surface of the rotor. As a result of this arrangement a minimum clearance is effectedbetween the rotor blades or lobes` overcome `and prevent a grabbing or freezing' of the rotors to the work faces when the apparatus isv operated at accelerated or abnormal the aircraft is flying in high altitudes.

Additional objects, aims and advantages of this invention will be apparent to persons skilled in the art after the construction and operation .of the apparatus is understood from the within description.

It is preferred to accomplish the numerous objects of this invention and to practice the same substantially in the manner hereinafter fully described land as more yparticularly pointed outv in the appended claim, reference being made to the accompanying drawings that form a part ofthis specification, wherein:

Fig. 1 is a fragmentary section of a fluid displacement apparatus embodying the improvements contemplated herein, the view being on the plane of line I-I cnFig. 2;

Fig 2 is a vertical section taken on the plano of line 2-2 en Fig. 1;

.Fig 3 is a sectional view on an exaggerated scale showing o ne of the preferred forms of this invention and a mannerof mounting the liner sheet on the housing wall; t

Fig. 4 is a` sectional view showing a liner sheet that comprises a metal screen or mesh; and

Fig. 5 is an explodedview of the structure shown in Fig. 4 and drawn to a larger scale. i

The drawings are to be understood as'being pose of disclosing typical or preferred forms in which the [improvements contemplated herein mayV be -made.` In these drawings like reference characters identify the same parts wherever theyl appear in the diiferent views.

The fluid displacement apparatus shown in Figs. 1 and 2' is preferably' a supercharger for internal combustion engines, but it will be understood that the improvements are adaptable to other types of apparatus. The housing comprises the arcuateor semi-cylindrical'end walls I0, a closure plate II for the open side of the housing, and a partition or back wall I2 opposite the open side. The top of the housing .is provided with an outlet stub I3 intermediate the 'semi-cylin-f drical walls I0, and there is an inlet stub I 4 in the bottom of the housing opposite the outlet stub. l Spaced 'parallel bearing bosses I5 thatl project from the back wall partition I2 provide journals for the shafts I6 and I1 that are rotatably mounted in said bosses so that their outer ends are projected beyond said bosses where they have intermeshed timing gears (not shown) secured to them, and one of said shafts is suitably coupled to a motor or other prime mover that is adapted to actuate the pump.

The rotors, which are preferably of the general shape of the blades of a Roots blower, each comprises pluralityY of lobe-shaped members or blades I8- extending radially from a central hub I 9 that isanchored to its respective shaft. The outer portions of these -blades or lobesY i8 that are adapted to sweep the arcuate work faces of the semi-cylindrical.walls III are preferably provided with parallel lands or ridges 20 that are cxtensive with the length of each of the blades and arevdisposed in spaced relation with respect te eacl'i" other at the tips ofther blades. The lobes or blades I8 are preferably of hollow construction with reinforcing ribs to .strengthen them, and the marginal edges of the lobe walls are preferably reduced in thickness by chamfering or under-cutting them as indicated at 2|. This provides a relatively narrow chisel-like shape for these work edges of the lobes or blades. 00 For the purpose of reducing the weight of the more or less of va schematic character for the purpump, the housing andthe rotors :hay be 4fabricated from. a light-weight metal such as an aluminurnalloy. This material howeverdoes not provide a sufficiently hard work face for .the housing walls and-it is not dependable in maintaining a minimum clearance betweenth'e working parts of a supercharger. To overcome these disadvantages, the `work faces of .the housing walls are provided with a liner 22 that comprises a thin sheet of material that is' harder than the aluminum alloy of the housing walls. It will be understood that the work faces of the housing are the inner surfaces of the semi-cylindrical walls I0, the inside .surface of the cover plate Il, and the surface of the partition 'or back wall I2, all of which surfaces are swept by the .rotors during operation of the pump. This liner i: de'- tacbably mounted on the aforesaid surfaces of changes and modifications.

the housingin a manner that permits its ready removal and replacement whenever desired. A

variety of types of these liners and attaching means-are disclosed in Figs. 3,4, and 5.

In Fig. 3 the housing wall, that is hereinafter identified as 1:. may be any of the housingr wals that has a work face adapted to be swept by the rotor. The liner 22 is a comparatively thin sheet of hard` material such as steel, and said liner sheet is attached to the'housing wall by means of a layer 25 of a commercial cement known underthe trade-name of Cycle-Weld that is manufactured and distributed by Cycleweld Division, Chrysler Motors Company, Detroit, Michigan. This cementitious material is applied tothe surfaces to be united perferably in a plastic state and it is allowed to set while the metal sheet' 22 is being pressed firmly against the housing wall.

The inner or exposed surface of-the liner shet face shown in Fig. 1. This exposed rough surface o f the mesh liner may be worn down or'dres'sed in the manner above described with reference to the grit blasted surface of the sheet metal liner.

While this invention has been described in detail in its present preferred forms or embodirents, it will be apparent to persons skilled in the art, after understanding the improvements contemplated herein.' that various changesand 'modifications may be made therein without departing from the spirit or scope thereof.

vliner plates; andr a pair of rotor members in said chamber, each of said rotor members having a plurality of blades and the blades of said rotor .members intermeshing, said rotor members and abrading surfaces initially being in frictionalicontact with n o clearance therebetween and said. blades having a hardness less 'than the hardness of said liner plates and having 'a higher coefficient ofexpansion than said liner plates. said abrading surfaces comprising minute protuberances and depressions of a depth in excess of that required to provide clearance for normal rotor speed and thermal expansion and suflicient to provide additional, operating clearance under conditions of abnormal speed and thermal expansion, whereby 22 mav be roughened as shown at 26 in Fig. 3 I

by blasting the surface with grit. After the parts of the pump are thus assembled, with practically no clearance between the rotors and the liner upon-rotation of Said rotor members at a given speed relative to said abrading surfaces the outer- A most peripheral portion and end faces of said Work faces of the housing walls, the pump is operated at normal speed which will effect an expansion of the parts due to the generated heat, and during this initial runnin".r of the 'oumn the ridges or lands 20 and the undercut edges 2`| of i the rotor walls will be dressed down and will wear awav a portion of the roughened work faces of the liners 22. so that the desired minimum clearances are obtained between the respective working parts of the pump.

In lieu of the metal sheet liner 22 hereinbefore described. the liner sheet may comprise a metal screen 30 that is formed by intermeshed or woven steel strips or steel wiresas shown in Figs. 4 and 5. In 'applying this tvpe of mesh or screen liner 30 to the housing wall :r the surfaces of these parts which oppose each other are sprayed with the Ty-Ply cement to provide a film 3| thereof on the under surface of the screen 30 and a film 32 of this cement`upon the surface of the housing wall :r to which the liner is to.be united. A ply of neoprene 33 is interposed between the thus prepared liner and housing wall and the assembled structure subjected to heat and pressure t'o cure the neoprene and unite the parts. A fiber mat, such as a Masonite board, is placed on the outer surface of the screen prior to the curing operation so that when the pressure is applied the mat will be forced into the interstices of the wire mesh and confine the neopreneback of the outer surface of this liner sheet. The metal mesh or screen provides a rough outer surface having the characteristics of the grit-blasted surblades will be automatically dressed down by said abrading surfaces to provide the necessary working clearance between said rotor members and liner plates for said given speed.

ROBERT P. vMCCULLOCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 878,480 Green Ju1y 16,1901 1,158,733 Shepherd et al 2- Nov. 2, 1915 1.631.359 Brown June '7, 1927 1,681.796 Wendell Aug. 21, 1928 1,686,867 Kuhn Oct. 9, 1928 1,784.866 Fahrenwald Dec. 16, 1930 1,785.386 McIntyre Dec. 16, 1930 1,828.409 Densmore Oct. 20, 1931 1,837,446 Kauffman Dec. 22, 1931 1,952,179 Milkowski et al Mar. 27, 1934 2,107,260 Ihara Feb. 1, 1938 2.121.068 Buechler June 21, 1938 2,167,311 Postma July 25, 1939 2.240.121 Patterson Apr. 29, 1941 2.345,975 Herman Apr. 4, 1944 2,491,677 McCulloch Dec. 20, 1949 FOREIGN PATENTS Number Country Date 207,907 Switzerland Apr. 1, 1940 464,475

Great Britain Apr. 1o, 1937 

